Ammunition consists of the projectiles and propelling charges used in small arms, artillery, and other guns. Ammunition size is usually expressed in terms of caliber, which is the diameter of the projectile as measured in millimeters or inches. In general, projectiles less than 20 mm or 0.60 inch in diameter are classified as small-arm, and larger calibers are considered artillery. A complete round of ammunition, which is referred to as a fixed type round, consists of all the components necessary for one firing of the gun. These normally included a projectile, the propellant, and a primer that ignites the propellant. Other components such as the cartridge case, fuze, and bursting charge are frequently included.
Small-arms ammunition is always of the fixed type. Complete rounds are usually called cartridges, and projectiles are called bullets. Cartridge cases or shells are most commonly made of brass, although steel is also widely used.
Handloading is the process used to create firearm cartridges by hand versus those put together en masse and sold commercially, generally in packages of 6 to 50. When previously-fired cases or shells are used, the process is often called reloading. The most common motivations for handloading cartridges are increased accuracy and cost savings, though handloaders may sacrifice one for the other. Reloading fired cases can save the shooter a significant amount of money, as the case is usually the major cost of a cartridge. The handloader can also create cartridges for which there are no commercial equivalents, such as wildcat cartridges. Collectors of obsolete firearms often have to handload since many obsolete cartridges are no longer commercially produced. Hunters may desire cartridges with specialized bullets. Target shooters seek optimum accuracy. Many handloaders customize their cartridges to their specific gun. This is usually in the pursuit of accuracy, though it can also lead to an increase in case life. For these specialty applications, cost is usually not a primary motivator, and such cartridges may cost more than commercial ones. As with any hobby, the pure enjoyment of the reloading process may well be the most important benefit.
There are three aspects to ballistics: internal ballistics, external ballistics, and terminal ballistics. Internal ballistics refers to the things which happen inside the weapon, before the bullet leaves the bore on firing. The handloading process can realize increased accuracy and precision through improved consistency of manufacture, and by customizing the weight and shape of the bullet, and tailoring the velocity of the bullet for best performance. Each cartridge loaded can have each component carefully matched to the rest of the cartridges in the batch. Brass cases can also be matched by volume and weight, bullets by weight and concentricity, powder charges by weight. Primers also play a role in accuracy and consistency, but the handloader usually has no ability to manufacture these, so the handloader is limited to experimenting with different primers available commercially. In addition to these items that are considered critical, the equipment used to assemble the cartridge also have an effect on its performance; dies used to size the cartridges can be matched to a given weapon's chamber, high precision scales can give more consistent and accurate measures of powder.
The operations performed when handloading are case cleaning, case inspection, remove the fired primer (reloading only), ream or swage crimp from primer pocket (reloading military cases only), lubricate the cases (variable) and resize the case (reloading only), measure and trim the case length (variable) (reloading only), expand the neck to accept the bullet, clean the lubricant from the cases (if applied), seat a new primer, add a volumetrically-measured or weighed amount of powder, seat the bullet in the case, and crimp the bullet in place (optional).
The basic piece of equipment for handloading is the press. A press is a device that uses compound leverage to push the cases into the dies that perform the loading operations. Presses vary from simple, inexpensive single stage models, to complex progressive models that will eject a loaded cartridge with each pull of a lever, at rates of 10 rounds a minute.
Single stage presses are the simplest. They perform one step on one case at a time. When using a single stage press, cases are loaded in batches, one step per batch at a time. Batches are normally small, about 50 cases at a time, so that a batch is not left in a partially completed state. Once a case is primed, it should be finished as soon as possible, since high humidity can degrade the primer.
Progressive presses handle several shells at once, with each pull of the lever performing a single step on all the cases at once. Progressive presses hold all the dies needed, plus a powder measure and a primer feed, and often also include an additional station where the powder levels are checked, to prevent over or under charges. Progressive presses also often feature case feeds that will hold hundreds of cases to be loaded, and all the user has to do is hold the bullet in place over the appropriate case mouth, and pull the lever.
Handloading is a complex and time-consuming process. Like any complex process, mistakes in handloading are easy to make, and it is far better to be safe and re-do a questionable step than to hope things will come out all right. Of all the steps involved in reloading, one of the most critical steps is the step of seating the bullet into the open end of the case or shell. If a bullet is not seated properly into the open end of the shell, it can dislodge or displace before reaching the next stage step in the handloading process. It is well understood among skilled artisans that a properly seated bullet is set neither too deep nor too shallow.
Skilled artisans have devoted considerable effort toward the development and improvement of handloading systems. However, current efforts have not yielded entirely accepetable results. For instance, known handloading systems are expensive, notoriously slow, cumbersome, require specialized skill, and fail to provide the precision tamping and seating of the bullet into the case or shell during the handloading process. Given these and other deficiencies prevelant in the art, the need for continued improvement is evident.